Christopher Badcock and Bernard Crespi, professors of sociology and biology, respectively, developed a new and intriguing hypothesis about the causes of severe disorders such as autism and schizophrenia. Under the titles “Imbalanced genomic imprinting in brain development: An evolutionary basis for the aetiology of autism” in Journal of Evolutionary Biology (2006) and “Battle of the sexes may set the brain” in Nature (2008), Professors Badcock and Crespi suggest that “A tug-of-war between the mother’s and father’s genes in the developing brain could explain a spectrum of mental disorders from autism to schizophrenia.”
In addition to challenging researchers with new ideas to test, their hypothesis is garnering coverage from the popular press. The story is being covered by New York Times, Discover, Autism Vox, and other sources. Part of the reason it’s getting this attention is that there are other implications of the hypothesis. For example, Professors Badcock and Crespi suggest that some scientists’ behavior—fascination with things and perseverance in analyzing them—may also be a result of the tension between gene expression.
Here’s the first couple of paragraphs of the essay from Nature>:
It has long been recognized that mental illnesses such as schizophrenia and autism tend to run in families. But neither disorder obeys classical Mendelian laws of inheritance, making it difficult to pinpoint the genes involved.
We believe that psychiatric illness may be less to do with the genes a mother and father pass down, and more to do with which genes they program for expression. By our hypothesis, a hidden battle of the sexes — where a mother’s egg and a father’s sperm engage in an evolutionary struggle to turn gene expression up or down — could play a crucial part in determining the balance or imbalance of an offspring’s brain. If this proves true, it would greatly clarify the diagnosis of mental disorders. It might even make it possible to reset the mind’s balance with targeted drugs.
And here is the abstract from their paper in Journal of Evolutionary Biology:
We describe a new hypothesis for the development of autism, that it is driven by imbalances in brain development involving enhanced effects of paternally expressed imprinted genes, deficits of effects from maternally expressed genes, or both. This hypothesis is supported by: (1) the strong genomic-imprinting component to the genetic and developmental mechanisms of autism, Angelman syndrome, Rett syndrome and Turner syndrome; (2) the core behavioural features of autism, such as self-focused behaviour, altered social interactions and language, and enhanced spatial and mechanistic cognition and abilities, and (3) the degree to which relevant brain functions and structures are altered in autism and related disorders. The imprinted brain theory of autism has important implications for understanding the genetic, epigenetic, neurological and cognitive bases of autism, as ultimately due to imbalances in the outcomes of intragenomic conflict between effects of maternally vs. paternally expressed genes.
Sources:
- Badcock, C., & Crespi, B. (2006). Imbalanced genomic imprinting in brain development: an evolutionary basis for the aetiology of autism. Journal of Evolutionary Biology, 19, 1007-1032;
- See Badcock, C., & Crespi, B. (2008). Battle of the sexes may set the brain. Nature 454, 1054-1055;
- “In a Novel Theory of Mental Disorders, Parents’ Genes Are in Competition” by Benedict Carey of the New York (NY, US) Times;
- “Mom and Dad Are Fighting in Your Genes—and in Your Brain” by Carl Zimmer in Discover;
- “New Theory About Autism and Genetics” by Kristina Chew of Autism Vox;
- Male brain vs. female brain I: Why do men try to figure out their relationships? Why do women talk to their cars?” by Satoshi Kanazawa in Psychology Today.
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